Installation guide

Creating a Mirrored LVM Logical Volume in a Cluster

5. Create the mirror. The first step is creating the physical volumes. The following commands create

three physical volumes. Two of the physical volumes will be used for the legs of the mirror, and the

third physical volume will contain the mirror log.

[root@doc-07 ~]# pvcreate /dev/xvdb1

Physical volume "/dev/xvdb1" successfully created

[root@doc-07 ~]# pvcreate /dev/xvdb2

Physical volume "/dev/xvdb2" successfully created

[root@doc-07 ~]# pvcreate /dev/xvdc1

Physical volume "/dev/xvdc1" successfully created

6. Create the volume group. This example creates a volume group vg001 that consists of the three

physical volumes that were created in the previous step.

[root@doc-07 ~]# vgcreate vg001 /dev/xvdb1 /dev/xvdb2 /dev/xvdc1

Clustered volume group "vg001" successfully created

Note that the output of the vgcreate command indicates that the volume group is clustered. You

can verify that a volume group is clustered with the vgs command, which will show the volume

group's attributes. If a volume group is clustered, it will show a c attribute.

[root@doc-07 ~]# vgs vg001

VG #PV #LV #SN Attr VSize VFree

vg001 3 0 0 wz--nc 68.97G 68.97G

7. Create the mirrored logical volume. This example creates the logical volume mirrorlv from the

volume group vg001. This volume has one mirror leg. This example specifies which extents of the

physical volume will be used for the logical volume.

[root@doc-07 ~]# lvcreate -l 1000 -m1 vg001 -n mirrorlv /dev/xvdb1:1-1000 /dev/

xvdb2:1-1000 /dev/xvdc1:0

Logical volume "mirrorlv" created

You can use the lvs command to display the progress of the mirror creation. The following

example shows that the mirror is 47% synced, then 91% synced, then 100% synced when the

mirror is complete.

[root@doc-07 log]# lvs vg001/mirrorlv

LV VG Attr LSize Origin Snap% Move Log Copy% Convert

mirrorlv vg001 mwi-a- 3.91G vg001_mlog 47.00

[root@doc-07 log]# lvs vg001/mirrorlv

LV VG Attr LSize Origin Snap% Move Log Copy% Convert

mirrorlv vg001 mwi-a- 3.91G vg001_mlog 91.00

[root@doc-07 ~]# lvs vg001/mirrorlv

LV VG Attr LSize Origin Snap% Move Log Copy% Convert

mirrorlv vg001 mwi-a- 3.91G vg001_mlog 100.00

The completion of the mirror is noted in the system log:

May 10 14:52:52 doc-07 [19402]: Monitoring mirror device vg001-mirrorlv for events